prompt: You will be provided with a partial code base and an issue statement explaining a problem to resolve.
  <issue>
  Change `export_file` to return `File` object
  **Context**
  
  In order to allow users to perform subsequent actions on an exported file (while maintaining a functional structure), we should allow the `export_file` function to return a file object.
  
  * Astro-SDK version: 0.9..1
  * Request by: @jlaneve
  * Analysed by @dimberman 
  
  **Problem**
  
  At the moment a user who wants to use the `output_file` object would need to explicitly set dependencies like this:
  
  ```
      output_file = File(path="/tmp/saved_df.csv")
      with sample_dag:
          table = aql.load_file(input_file=File(path=data_path), output_table=test_table)
          export = aql.export_file(
              input_data=table,
              output_file=output_file,
              if_exists="replace",
          )
          res_df = aql.load_file(input_file=output_file)
          export >> res_df
  ```
  
  **Desired behaviour**
  
  ```
      with sample_dag:
          table = aql.load_file(input_file=File(path=data_path), output_table=test_table)
          exported_file = aql.export_file(
              input_data=table,
              output_file=File(path="/tmp/saved_df.csv"),
              if_exists="replace",
          )
          res_df = aql.load_file(input_file=exported_file)
  ```
  
  **Acceptance criteria**
  * Change `export_file` so it returns the `File` instance, as opposed to `None`
  
  Since there is no documentation about this task, we don't need to update the documentation for it. To create documentation for this feature should be part of another issue.
  
  </issue>
  <code>
  [start of src/astro/sql/operators/export_file.py]
  1 from typing import Optional, Union
  2 
  3 import pandas as pd
  4 from airflow.models import BaseOperator
  5 from airflow.models.xcom_arg import XComArg
  6 
  7 from astro.constants import ExportExistsStrategy
  8 from astro.databases import create_database
  9 from astro.files import File
  10 from astro.sql.table import Table
  11 from astro.utils.task_id_helper import get_task_id
  12 
  13 
  14 class ExportFile(BaseOperator):
  15     """Write SQL table to csv/parquet on local/S3/GCS.
  16 
  17     :param input_data: Table to convert to file
  18     :param output_file: File object containing the path to the file and connection id.
  19     :param if_exists: Overwrite file if exists. Default False.
  20     """
  21 
  22     template_fields = ("input_data", "output_file")
  23 
  24     def __init__(
  25         self,
  26         input_data: Union[Table, pd.DataFrame],
  27         output_file: File,
  28         if_exists: ExportExistsStrategy = "exception",
  29         **kwargs,
  30     ) -> None:
  31         super().__init__(**kwargs)
  32         self.output_file = output_file
  33         self.input_data = input_data
  34         self.if_exists = if_exists
  35         self.kwargs = kwargs
  36 
  37     def execute(self, context: dict) -> None:
  38         """Write SQL table to csv/parquet on local/S3/GCS.
  39 
  40         Infers SQL database type based on connection.
  41         """
  42         # Infer db type from `input_conn_id`.
  43         if isinstance(self.input_data, Table):
  44             database = create_database(self.input_data.conn_id)
  45             self.input_data = database.populate_table_metadata(self.input_data)
  46             df = database.export_table_to_pandas_dataframe(self.input_data)
  47         elif isinstance(self.input_data, pd.DataFrame):
  48             df = self.input_data
  49         else:
  50             raise ValueError(
  51                 f"Expected input_table to be Table or dataframe. Got {type(self.input_data)}"
  52             )
  53         # Write file if overwrite == True or if file doesn't exist.
  54         if self.if_exists == "replace" or not self.output_file.exists():
  55             self.output_file.create_from_dataframe(df)
  56         else:
  57             raise FileExistsError(f"{self.output_file.path} file already exists.")
  58 
  59 
  60 def export_file(
  61     input_data: Union[Table, pd.DataFrame],
  62     output_file: File,
  63     if_exists: ExportExistsStrategy = "exception",
  64     task_id: Optional[str] = None,
  65     **kwargs,
  66 ) -> XComArg:
  67     """Convert SaveFile into a function. Returns XComArg.
  68 
  69     Returns an XComArg object.
  70 
  71     :param output_file: Path and conn_id
  72     :param input_data: Input table / dataframe
  73     :param if_exists: Overwrite file if exists. Default "exception"
  74     :param task_id: task id, optional
  75     """
  76 
  77     task_id = (
  78         task_id if task_id is not None else get_task_id("export_file", output_file.path)
  79     )
  80 
  81     return ExportFile(
  82         task_id=task_id,
  83         output_file=output_file,
  84         input_data=input_data,
  85         if_exists=if_exists,
  86     ).output
  87
  [end of src/astro/sql/operators/export_file.py]
  </code>
  
  I need you to solve this issue by generating a single patch file that I can apply directly to this repository using git apply. Please respond with a single patch file in the following format.
  <patch>
  diff --git a/file.py b/file.py
  --- a/file.py
  +++ b/file.py
  @@ -1,27 +1,35 @@
   def euclidean(a, b):
  -    while b:
  -        a, b = b, a % b
  -    return a
  +    if b == 0:
  +        return a
  +    return euclidean(b, a % b)
   
   
   def bresenham(x0, y0, x1, y1):
       points = []
       dx = abs(x1 - x0)
       dy = abs(y1 - y0)
  -    sx = 1 if x0 < x1 else -1
  -    sy = 1 if y0 < y1 else -1
  -    err = dx - dy
  +    x, y = x0, y0
  +    sx = -1 if x0 > x1 else 1
  +    sy = -1 if y0 > y1 else 1
   
  -    while True:
  -        points.append((x0, y0))
  -        if x0 == x1 and y0 == y1:
  -            break
  -        e2 = 2 * err
  -        if e2 > -dy:
  -            err -= dy
  -            x0 += sx
  -        if e2 < dx:
  -            err += dx
  -            y0 += sy
  +    if dx > dy:
  +        err = dx / 2.0
  +        while x != x1:
  +            points.append((x, y))
  +            err -= dy
  +            if err < 0:
  +                y += sy
  +                err += dx
  +            x += sx
  +    else:
  +        err = dy / 2.0
  +        while y != y1:
  +            points.append((x, y))
  +            err -= dx
  +            if err < 0:
  +                x += sx
  +                err += dy
  +            y += sy
  +
  +    points.append((x, y))
       return points
  
  </patch>
golden_diff: diff --git a/src/astro/sql/operators/export_file.py b/src/astro/sql/operators/export_file.py
  --- a/src/astro/sql/operators/export_file.py
  +++ b/src/astro/sql/operators/export_file.py
  @@ -34,7 +34,7 @@
           self.if_exists = if_exists
           self.kwargs = kwargs
   
  -    def execute(self, context: dict) -> None:
  +    def execute(self, context: dict) -> File:
           """Write SQL table to csv/parquet on local/S3/GCS.
   
           Infers SQL database type based on connection.
  @@ -53,6 +53,7 @@
           # Write file if overwrite == True or if file doesn't exist.
           if self.if_exists == "replace" or not self.output_file.exists():
               self.output_file.create_from_dataframe(df)
  +            return self.output_file
           else:
               raise FileExistsError(f"{self.output_file.path} file already exists.")
   
  @@ -66,7 +67,20 @@
   ) -> XComArg:
       """Convert SaveFile into a function. Returns XComArg.
   
  -    Returns an XComArg object.
  +    Returns an XComArg object of type File which matches the output_file parameter.
  +
  +    This will allow users to perform further actions with the exported file.
  +
  +    e.g.
  +
  +        with sample_dag:
  +        table = aql.load_file(input_file=File(path=data_path), output_table=test_table)
  +        exported_file = aql.export_file(
  +            input_data=table,
  +            output_file=File(path="/tmp/saved_df.csv"),
  +            if_exists="replace",
  +        )
  +        res_df = aql.load_file(input_file=exported_file)
   
       :param output_file: Path and conn_id
       :param input_data: Input table / dataframe
  
verification_info: {"golden_diff": "diff --git a/src/astro/sql/operators/export_file.py b/src/astro/sql/operators/export_file.py\n--- a/src/astro/sql/operators/export_file.py\n+++ b/src/astro/sql/operators/export_file.py\n@@ -34,7 +34,7 @@\n         self.if_exists = if_exists\n         self.kwargs = kwargs\n \n-    def execute(self, context: dict) -> None:\n+    def execute(self, context: dict) -> File:\n         \"\"\"Write SQL table to csv/parquet on local/S3/GCS.\n \n         Infers SQL database type based on connection.\n@@ -53,6 +53,7 @@\n         # Write file if overwrite == True or if file doesn't exist.\n         if self.if_exists == \"replace\" or not self.output_file.exists():\n             self.output_file.create_from_dataframe(df)\n+            return self.output_file\n         else:\n             raise FileExistsError(f\"{self.output_file.path} file already exists.\")\n \n@@ -66,7 +67,20 @@\n ) -> XComArg:\n     \"\"\"Convert SaveFile into a function. Returns XComArg.\n \n-    Returns an XComArg object.\n+    Returns an XComArg object of type File which matches the output_file parameter.\n+\n+    This will allow users to perform further actions with the exported file.\n+\n+    e.g.\n+\n+        with sample_dag:\n+        table = aql.load_file(input_file=File(path=data_path), output_table=test_table)\n+        exported_file = aql.export_file(\n+            input_data=table,\n+            output_file=File(path=\"/tmp/saved_df.csv\"),\n+            if_exists=\"replace\",\n+        )\n+        res_df = aql.load_file(input_file=exported_file)\n \n     :param output_file: Path and conn_id\n     :param input_data: Input table / dataframe\n", "issue": "Change `export_file` to return `File` object\n**Context**\r\n\r\nIn order to allow users to perform subsequent actions on an exported file (while maintaining a functional structure), we should allow the `export_file` function to return a file object.\r\n\r\n* Astro-SDK version: 0.9..1\r\n* Request by: @jlaneve\r\n* Analysed by @dimberman \r\n\r\n**Problem**\r\n\r\nAt the moment a user who wants to use the `output_file` object would need to explicitly set dependencies like this:\r\n\r\n```\r\n    output_file = File(path=\"/tmp/saved_df.csv\")\r\n    with sample_dag:\r\n        table = aql.load_file(input_file=File(path=data_path), output_table=test_table)\r\n        export = aql.export_file(\r\n            input_data=table,\r\n            output_file=output_file,\r\n            if_exists=\"replace\",\r\n        )\r\n        res_df = aql.load_file(input_file=output_file)\r\n        export >> res_df\r\n```\r\n\r\n**Desired behaviour**\r\n\r\n```\r\n    with sample_dag:\r\n        table = aql.load_file(input_file=File(path=data_path), output_table=test_table)\r\n        exported_file = aql.export_file(\r\n            input_data=table,\r\n            output_file=File(path=\"/tmp/saved_df.csv\"),\r\n            if_exists=\"replace\",\r\n        )\r\n        res_df = aql.load_file(input_file=exported_file)\r\n```\r\n\r\n**Acceptance criteria**\r\n* Change `export_file` so it returns the `File` instance, as opposed to `None`\r\n\r\nSince there is no documentation about this task, we don't need to update the documentation for it. To create documentation for this feature should be part of another issue.\n", "before_files": [{"content": "from typing import Optional, Union\n\nimport pandas as pd\nfrom airflow.models import BaseOperator\nfrom airflow.models.xcom_arg import XComArg\n\nfrom astro.constants import ExportExistsStrategy\nfrom astro.databases import create_database\nfrom astro.files import File\nfrom astro.sql.table import Table\nfrom astro.utils.task_id_helper import get_task_id\n\n\nclass ExportFile(BaseOperator):\n    \"\"\"Write SQL table to csv/parquet on local/S3/GCS.\n\n    :param input_data: Table to convert to file\n    :param output_file: File object containing the path to the file and connection id.\n    :param if_exists: Overwrite file if exists. Default False.\n    \"\"\"\n\n    template_fields = (\"input_data\", \"output_file\")\n\n    def __init__(\n        self,\n        input_data: Union[Table, pd.DataFrame],\n        output_file: File,\n        if_exists: ExportExistsStrategy = \"exception\",\n        **kwargs,\n    ) -> None:\n        super().__init__(**kwargs)\n        self.output_file = output_file\n        self.input_data = input_data\n        self.if_exists = if_exists\n        self.kwargs = kwargs\n\n    def execute(self, context: dict) -> None:\n        \"\"\"Write SQL table to csv/parquet on local/S3/GCS.\n\n        Infers SQL database type based on connection.\n        \"\"\"\n        # Infer db type from `input_conn_id`.\n        if isinstance(self.input_data, Table):\n            database = create_database(self.input_data.conn_id)\n            self.input_data = database.populate_table_metadata(self.input_data)\n            df = database.export_table_to_pandas_dataframe(self.input_data)\n        elif isinstance(self.input_data, pd.DataFrame):\n            df = self.input_data\n        else:\n            raise ValueError(\n                f\"Expected input_table to be Table or dataframe. Got {type(self.input_data)}\"\n            )\n        # Write file if overwrite == True or if file doesn't exist.\n        if self.if_exists == \"replace\" or not self.output_file.exists():\n            self.output_file.create_from_dataframe(df)\n        else:\n            raise FileExistsError(f\"{self.output_file.path} file already exists.\")\n\n\ndef export_file(\n    input_data: Union[Table, pd.DataFrame],\n    output_file: File,\n    if_exists: ExportExistsStrategy = \"exception\",\n    task_id: Optional[str] = None,\n    **kwargs,\n) -> XComArg:\n    \"\"\"Convert SaveFile into a function. Returns XComArg.\n\n    Returns an XComArg object.\n\n    :param output_file: Path and conn_id\n    :param input_data: Input table / dataframe\n    :param if_exists: Overwrite file if exists. Default \"exception\"\n    :param task_id: task id, optional\n    \"\"\"\n\n    task_id = (\n        task_id if task_id is not None else get_task_id(\"export_file\", output_file.path)\n    )\n\n    return ExportFile(\n        task_id=task_id,\n        output_file=output_file,\n        input_data=input_data,\n        if_exists=if_exists,\n    ).output\n", "path": "src/astro/sql/operators/export_file.py"}]}