def get_context_keys_for_custom_policy(PolicyInputList=None):
    """
    Gets a list of all of the context keys referenced in the input policies. The policies are supplied as a list of one or more strings. To get the context keys from policies associated with an IAM user, group, or role, use  GetContextKeysForPrincipalPolicy .
    Context keys are variables maintained by AWS and its services that provide details about the context of an API query request, and can be evaluated by testing against a value specified in an IAM policy. Use GetContextKeysForCustomPolicy to understand what key names and values you must supply when you call  SimulateCustomPolicy . Note that all parameters are shown in unencoded form here for clarity, but must be URL encoded to be included as a part of a real HTML request.
    See also: AWS API Documentation
    
    
    :example: response = client.get_context_keys_for_custom_policy(
        PolicyInputList=[
            'string',
        ]
    )
    
    
    :type PolicyInputList: list
    :param PolicyInputList: [REQUIRED]
            A list of policies for which you want the list of context keys referenced in those policies. Each document is specified as a string containing the complete, valid JSON text of an IAM policy.
            The regex pattern used to validate this parameter is a string of characters consisting of any printable ASCII character ranging from the space character (u0020) through end of the ASCII character range as well as the printable characters in the Basic Latin and Latin-1 Supplement character set (through u00FF). It also includes the special characters tab (u0009), line feed (u000A), and carriage return (u000D).
            (string) --
            

    :rtype: dict
    :return: {
        'ContextKeyNames': [
            'string',
        ]
    }
    
    
    :returns: 
    (string) --
    
    """
    pass
