code: def parse_schema_definition(parser):
      start = parser.token.start
      expect_keyword(parser, "schema")
      directives = parse_directives(parser)
      operation_types = many(
          parser,
          TokenKind.BRACE_L,
          parse_operation_type_definition,
          TokenKind.BRACE_R,
      )
  
      return ast.SchemaDefinition(
          directives=directives,
          operation_types=operation_types,
          loc=loc(parser, start),
      )
  
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 39 for calling a global function with example usage: parse_schema_definition(parser) and returns: ast