code: def parse_operation_type(parser):
      operation_token = expect(parser, TokenKind.NAME)
      operation = operation_token.value
      if operation == "query":
          return "query"
      elif operation == "mutation":
          return "mutation"
      elif operation == "subscription":
          return "subscription"
  
      raise unexpected(parser, operation_token)
  
imports: from .None import ast
  from ..error import GraphQLSyntaxError
  from .lexer import Lexer, TokenKind, get_token_desc, get_token_kind_desc
  from .source import Source
label_desc: Use image node_id 16 for calling a global function with example usage: parse_operation_type(parser) and returns: str, str, str