class_docstr: Namespace for list related expressions.
class_docstr_tok: ["Namespace","for","list","related","expressions","."]
docstr: Join all string items in a sublist and place a separator between them.
  
  This errors if inner type of list `!= String`.
  
  Parameters
  ----------
  separator
      string to separate the items with
  
  Returns
  -------
  Expr
      Expression of data type :class:`String`.
  
  Examples
  --------
  >>> df = pl.DataFrame({"s": [["a", "b", "c"], ["x", "y"]]})
  >>> df.with_columns(join=pl.col("s").list.join(" "))
  shape: (2, 2)
  ┌─────────────────┬───────┐
  │ s               ┆ join  │
  │ ---             ┆ ---   │
  │ list[str]       ┆ str   │
  ╞═════════════════╪═══════╡
  │ ["a", "b", "c"] ┆ a b c │
  │ ["x", "y"]      ┆ x y   │
  └─────────────────┴───────┘
  
  >>> df = pl.DataFrame(
  ...     {"s": [["a", "b", "c"], ["x", "y"]], "separator": ["*", "_"]}
  ... )
  >>> df.with_columns(join=pl.col("s").list.join(pl.col("separator")))
  shape: (2, 3)
  ┌─────────────────┬───────────┬───────┐
  │ s               ┆ separator ┆ join  │
  │ ---             ┆ ---       ┆ ---   │
  │ list[str]       ┆ str       ┆ str   │
  ╞═════════════════╪═══════════╪═══════╡
  │ ["a", "b", "c"] ┆ *         ┆ a*b*c │
  │ ["x", "y"]      ┆ _         ┆ x_y   │
  └─────────────────┴───────────┴───────┘
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code: def join(self, separator: IntoExpr) -> Expr:
      """
      Join all string items in a sublist and place a separator between them.
  
      This errors if inner type of list `!= String`.
  
      Parameters
      ----------
      separator
          string to separate the items with
  
      Returns
      -------
      Expr
          Expression of data type :class:`String`.
  
      Examples
      --------
      >>> df = pl.DataFrame({"s": [["a", "b", "c"], ["x", "y"]]})
      >>> df.with_columns(join=pl.col("s").list.join(" "))
      shape: (2, 2)
      ┌─────────────────┬───────┐
      │ s               ┆ join  │
      │ ---             ┆ ---   │
      │ list[str]       ┆ str   │
      ╞═════════════════╪═══════╡
      │ ["a", "b", "c"] ┆ a b c │
      │ ["x", "y"]      ┆ x y   │
      └─────────────────┴───────┘
  
      >>> df = pl.DataFrame(
      ...     {"s": [["a", "b", "c"], ["x", "y"]], "separator": ["*", "_"]}
      ... )
      >>> df.with_columns(join=pl.col("s").list.join(pl.col("separator")))
      shape: (2, 3)
      ┌─────────────────┬───────────┬───────┐
      │ s               ┆ separator ┆ join  │
      │ ---             ┆ ---       ┆ ---   │
      │ list[str]       ┆ str       ┆ str   │
      ╞═════════════════╪═══════════╪═══════╡
      │ ["a", "b", "c"] ┆ *         ┆ a*b*c │
      │ ["x", "y"]      ┆ _         ┆ x_y   │
      └─────────────────┴───────────┴───────┘
  
      """
      separator = parse_as_expression(separator, str_as_lit=True)
      return wrap_expr(self._pyexpr.list_join(separator))
  
imports: from __future__ import annotations
  import copy
  from typing import TYPE_CHECKING, Any, Callable, Sequence
  import polars._reexport
  from polars import functions
  from polars.utils._parse_expr_input import parse_as_expression
  from polars.utils._wrap import wrap_expr
  from polars.utils.deprecation import deprecate_renamed_function, deprecate_renamed_parameter
label_desc: Use image node_id 21 for calling the ExprListNameSpace obj's underlying member method code with example usage: obj.join(separator) and returns: wrap_expr