code: def p_map_type(self, p):
          '''map_type : MAP '<' field_type ',' field_type '>' annotations'''
          p[0] = ast.MapType(key_type=p[3], value_type=p[5], annotations=p[7]f p_map_type(self, p):
          '''map_type : MAP '<' field_type ',' field_type '>' annotations'''
          p[0] = ast.MapType(key_type=p[3], value_type=p[5], annotations=p[7])
docs: map_type : MAP '<' field_type ',' field_type '>' annotations