code: def _leaf_op(op_name: str) -> Expression:
      gateway = get_gateway()
      return Expression(getattr(gateway.jvm.Expressions, op_name)())
  
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 1 for calling a global function with example usage: _leaf_op(op_name) and returns: Expression