<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def parse( self, argmap, req=None, locations=None, validate=None, error_status_code=None, error_headers=None, ):
 """Main request parsing method. :param argmap: Either a `marshmallow.Schema`, a `dict` of argname -> `marshmallow.fields.Field` pairs, or a callable which accepts a request and returns a `marshmallow.Schema`. :param req: The request object to parse. :param tuple locations: Where on the request to search for values. Can include one or more of ``('json', 'querystring', 'form', 'headers', 'cookies', 'files')``. :param callable validate: Validation function or list of validation functions that receives the dictionary of parsed arguments. Validator either returns a boolean or raises a :exc:`ValidationError`. :param int error_status_code: Status code passed to error handler functions when a `ValidationError` is raised. :param dict error_headers: Headers passed to error handler functions when a a `ValidationError` is raised. :return: A dictionary of parsed arguments """

        self.clear_cache()  # in case someone used `parse_*()`
        req = req if req is not None else self.get_default_request()
        assert req is not None, "Must pass req object"
        data = None
        validators = _ensure_list_of_callables(validate)
        parser = self._clone()
        schema = self._get_schema(argmap, req)
        try:
            parsed = parser._parse_request(
                schema=schema, req=req, locations=locations or self.locations
            )
            result = schema.load(parsed)
            data = result.data if MARSHMALLOW_VERSION_INFO[0] < 3 else result
            parser._validate_arguments(data, validators)
        except ma.exceptions.ValidationError as error:
            parser._on_validation_error(
                error, req, schema, error_status_code, error_headers
            )
        return data