class_docstr: The base class for generating different tasks
  
  Example 1:
  
      input: a specific task template and rolling steps
  
      output: rolling version of the tasks
  
  Example 2:
  
      input: a specific task template and losses list
  
      output: a set of tasks with different losses
docstr: This is just a syntactic sugar for generate
docstr_tok: ["This","is","just","a","syntactic","sugar","for","generate"]
code: def __call__(self, *args, **kwargs):
      """
      This is just a syntactic sugar for generate
      """
      return self.generate(*args, **kwargs)
  
imports: import abc
  import copy
  import pandas
  from typing import Dict, List, Union, Callable
  from qlib.utils import transform_end_date
  from .utils import TimeAdjuster
label_desc: Use image node_id 2 for calling the TaskGen obj's underlying member method code with example usage: obj.__call__() and returns: self