code: def pi() -> Expression[float]:
      """
      Returns a value that is closer than any other value to `pi`.
      """
      return _leaf_op("pi")
  
imports: from typing import Union
  from pyflink import add_version_doc
  from pyflink.java_gateway import get_gateway
  from pyflink.table.expression import Expression, _get_java_expression, TimePointUnit, JsonOnNull
  from pyflink.table.types import _to_java_data_type, DataType
  from pyflink.table.udf import UserDefinedFunctionWrapper
  from pyflink.util.java_utils import to_jarray, load_java_class
label_desc: Use image node_id 35 for calling a global function with example usage: pi() and returns: _leaf_op