class_docstr: Static Expression
  
  This kind of feature will load data from provider
class_docstr_tok: ["Static","Expression","This","kind","of","feature","will","load","data","from","provider"]
code: def __str__(self):
      return "$" + self._name
  
imports: from __future__ import division
  from __future__ import print_function
  import abc
  import pandas
  from ..log import get_module_logger
label_desc: Use image node_id 2 for calling the Feature obj's underlying member method code with example usage: obj.__str__() and returns: unknown