class_docstr: Create a new alias as a key-value pair. All aliases are stored
  in ``Alias.aliases``. Duplicate keys or values are not allowed,
  unless the ``replace`` parameter is ``True``.
  
  Parameters
  ----------
  name : str
      Alias key.
  expr : str
      Alias value.
  replace : bool, optional
      Replace the current key-value pair if it already exists.
  
  Attributes
  ----------
  Alias.aliases : dict
      Class variable for storing all known aliases
  
  Examples
  --------
  
  >>> Alias('atr', 'ma_truerange')
  >>> Alias('hc', 'higher_close')
code: def __str__(self):
      return self.expr
  
file_path: AlphaPy/alphapy/alias.py
imports: import logging
  import parser
  import re
label_desc: Use image node_id 3 for calling the Alias obj's underlying member method code with example usage: obj.__str__() and returns: self