prompt: We are currently solving the following issue within our repository. Here is the issue text:
  --- BEGIN ISSUE ---
  Most YAML documents use document starts (---)
  Hi,
  
  I am the creator of yamllint, the linter coala uses for YAML.
  
  Since #965 was merged three months ago, coala fails on many projects like Ansible, OpenStack and even yamllint itself, because coala doesn't accept document start markers (`---`) anymore.
  
  Document start markers are commonly used, and required when declaring multiple documents in a single `.yaml` file (see [the spec](http://yaml.org/spec/1.2/spec.html#id2800132)).
  
  The proposed fix in the original issue (#923) was to disable the rule, but the implemented fix (#965) made document starts forbidden.
  
  My opinion is that coala should either require document starts, or disable the rule by default.
  
  --- END ISSUE ---
  
  Below are some code segments, each from a relevant file. One or more of these files may contain bugs.
  --- BEGIN FILES ---
  Path: `bears/yaml/YAMLLintBear.py`
  Content:
  ```
  1 from coalib.bearlib.abstractions.Linter import linter
  2 from dependency_management.requirements.PipRequirement import PipRequirement
  3 import yaml
  4 
  5 
  6 @linter(executable='yamllint',
  7         output_format='regex',
  8         output_regex=r'.+:(?P<line>\d+):(?P<column>\d+): '
  9                      r'\[(?P<severity>error|warning)\] (?P<message>.+)')
  10 class YAMLLintBear:
  11     """
  12     Check yaml code for errors and possible problems.
  13 
  14     You can read more about capabilities at
  15     <http://yamllint.readthedocs.org/en/latest/rules.html>.
  16     """
  17 
  18     LANGUAGES = {'YAML'}
  19     REQUIREMENTS = {PipRequirement('yamllint', '1.5')}
  20     AUTHORS = {'The coala developers'}
  21     AUTHORS_EMAILS = {'coala-devel@googlegroups.com'}
  22     LICENSE = 'AGPL-3.0'
  23     CAN_DETECT = {'Syntax', 'Formatting'}
  24 
  25     @staticmethod
  26     def generate_config(filename, file,
  27                         document_start: bool=False):
  28         """
  29         :param document_start:
  30             Use this rule to require or forbid the use of document start
  31             marker (---).
  32         """
  33         yamllint_configs = {
  34             'extends': 'default',
  35             'rules': {
  36                 'document-start': {
  37                     'present': False
  38                  }
  39             }
  40         }
  41         if document_start:
  42             yamllint_configs['rules']['document-start']['present'] = True
  43 
  44         return yaml.dump(yamllint_configs)
  45 
  46     @staticmethod
  47     def create_arguments(filename, file, config_file, yamllint_config: str=''):
  48         """
  49         :param yamllint_config: Path to a custom configuration file.
  50         """
  51         args = ('-f', 'parsable', filename)
  52         if yamllint_config:
  53             args += ('--config-file=' + yamllint_config,)
  54         else:
  55             args += ('--config-file=' + config_file,)
  56         return args
  57
  ```
  --- END FILES ---
  
  Please first localize the bug based on the issue statement, and then generate a patch according to the `git diff` format fenced by three backticks.
  
  Here is an example:
  
  ```diff
  diff --git a/examples/server_async.py b/examples/server_async.py
  --- a/examples/server_async.py
  +++ b/examples/server_async.py
  @@ -313,4 +313,4 @@
   
   
   if __name__ == "__main__":
  -    asyncio.run(run_async_server("."), debug=True)
  +    asyncio.run(run_async_server(), debug=True)
  diff --git a/examples/server_sync.py b/examples/server_sync.py
  --- a/examples/server_sync.py
  +++ b/examples/server_sync.py
  @@ -313,5 +313,5 @@
   
   
   if __name__ == "__main__":
  -    server = run_sync_server(".")
  +    server = run_sync_server()
       server.shutdown()
  
  ```
  
golden_diff: diff --git a/bears/yaml/YAMLLintBear.py b/bears/yaml/YAMLLintBear.py
  --- a/bears/yaml/YAMLLintBear.py
  +++ b/bears/yaml/YAMLLintBear.py
  @@ -24,7 +24,7 @@
   
       @staticmethod
       def generate_config(filename, file,
  -                        document_start: bool=False):
  +                        document_start: bool=None):
           """
           :param document_start:
               Use this rule to require or forbid the use of document start
  @@ -33,13 +33,10 @@
           yamllint_configs = {
               'extends': 'default',
               'rules': {
  -                'document-start': {
  -                    'present': False
  -                 }
  -            }
  +                'document-start': 'disable' if document_start is None
  +                                  else {'present': document_start},
  +            },
           }
  -        if document_start:
  -            yamllint_configs['rules']['document-start']['present'] = True
   
           return yaml.dump(yamllint_configs)
  
verification_info: {"golden_diff": "diff --git a/bears/yaml/YAMLLintBear.py b/bears/yaml/YAMLLintBear.py\n--- a/bears/yaml/YAMLLintBear.py\n+++ b/bears/yaml/YAMLLintBear.py\n@@ -24,7 +24,7 @@\n \n     @staticmethod\n     def generate_config(filename, file,\n-                        document_start: bool=False):\n+                        document_start: bool=None):\n         \"\"\"\n         :param document_start:\n             Use this rule to require or forbid the use of document start\n@@ -33,13 +33,10 @@\n         yamllint_configs = {\n             'extends': 'default',\n             'rules': {\n-                'document-start': {\n-                    'present': False\n-                 }\n-            }\n+                'document-start': 'disable' if document_start is None\n+                                  else {'present': document_start},\n+            },\n         }\n-        if document_start:\n-            yamllint_configs['rules']['document-start']['present'] = True\n \n         return yaml.dump(yamllint_configs)\n", "issue": "Most YAML documents use document starts (---)\nHi,\r\n\r\nI am the creator of yamllint, the linter coala uses for YAML.\r\n\r\nSince #965 was merged three months ago, coala fails on many projects like Ansible, OpenStack and even yamllint itself, because coala doesn't accept document start markers (`---`) anymore.\r\n\r\nDocument start markers are commonly used, and required when declaring multiple documents in a single `.yaml` file (see [the spec](http://yaml.org/spec/1.2/spec.html#id2800132)).\r\n\r\nThe proposed fix in the original issue (#923) was to disable the rule, but the implemented fix (#965) made document starts forbidden.\r\n\r\nMy opinion is that coala should either require document starts, or disable the rule by default.\n", "before_files": [{"content": "from coalib.bearlib.abstractions.Linter import linter\nfrom dependency_management.requirements.PipRequirement import PipRequirement\nimport yaml\n\n\n@linter(executable='yamllint',\n        output_format='regex',\n        output_regex=r'.+:(?P<line>\\d+):(?P<column>\\d+): '\n                     r'\\[(?P<severity>error|warning)\\] (?P<message>.+)')\nclass YAMLLintBear:\n    \"\"\"\n    Check yaml code for errors and possible problems.\n\n    You can read more about capabilities at\n    <http://yamllint.readthedocs.org/en/latest/rules.html>.\n    \"\"\"\n\n    LANGUAGES = {'YAML'}\n    REQUIREMENTS = {PipRequirement('yamllint', '1.5')}\n    AUTHORS = {'The coala developers'}\n    AUTHORS_EMAILS = {'coala-devel@googlegroups.com'}\n    LICENSE = 'AGPL-3.0'\n    CAN_DETECT = {'Syntax', 'Formatting'}\n\n    @staticmethod\n    def generate_config(filename, file,\n                        document_start: bool=False):\n        \"\"\"\n        :param document_start:\n            Use this rule to require or forbid the use of document start\n            marker (---).\n        \"\"\"\n        yamllint_configs = {\n            'extends': 'default',\n            'rules': {\n                'document-start': {\n                    'present': False\n                 }\n            }\n        }\n        if document_start:\n            yamllint_configs['rules']['document-start']['present'] = True\n\n        return yaml.dump(yamllint_configs)\n\n    @staticmethod\n    def create_arguments(filename, file, config_file, yamllint_config: str=''):\n        \"\"\"\n        :param yamllint_config: Path to a custom configuration file.\n        \"\"\"\n        args = ('-f', 'parsable', filename)\n        if yamllint_config:\n            args += ('--config-file=' + yamllint_config,)\n        else:\n            args += ('--config-file=' + config_file,)\n        return args\n", "path": "bears/yaml/YAMLLintBear.py"}], "after_files": [{"content": "from coalib.bearlib.abstractions.Linter import linter\nfrom dependency_management.requirements.PipRequirement import PipRequirement\nimport yaml\n\n\n@linter(executable='yamllint',\n        output_format='regex',\n        output_regex=r'.+:(?P<line>\\d+):(?P<column>\\d+): '\n                     r'\\[(?P<severity>error|warning)\\] (?P<message>.+)')\nclass YAMLLintBear:\n    \"\"\"\n    Check yaml code for errors and possible problems.\n\n    You can read more about capabilities at\n    <http://yamllint.readthedocs.org/en/latest/rules.html>.\n    \"\"\"\n\n    LANGUAGES = {'YAML'}\n    REQUIREMENTS = {PipRequirement('yamllint', '1.5')}\n    AUTHORS = {'The coala developers'}\n    AUTHORS_EMAILS = {'coala-devel@googlegroups.com'}\n    LICENSE = 'AGPL-3.0'\n    CAN_DETECT = {'Syntax', 'Formatting'}\n\n    @staticmethod\n    def generate_config(filename, file,\n                        document_start: bool=None):\n        \"\"\"\n        :param document_start:\n            Use this rule to require or forbid the use of document start\n            marker (---).\n        \"\"\"\n        yamllint_configs = {\n            'extends': 'default',\n            'rules': {\n                'document-start': 'disable' if document_start is None\n                                  else {'present': document_start},\n            },\n        }\n\n        return yaml.dump(yamllint_configs)\n\n    @staticmethod\n    def create_arguments(filename, file, config_file, yamllint_config: str=''):\n        \"\"\"\n        :param yamllint_config: Path to a custom configuration file.\n        \"\"\"\n        args = ('-f', 'parsable', filename)\n        if yamllint_config:\n            args += ('--config-file=' + yamllint_config,)\n        else:\n            args += ('--config-file=' + config_file,)\n        return args\n", "path": "bears/yaml/YAMLLintBear.py"}]}