docstr: Sets the reference value to compute the delta. By default, it
  is set to the current value.
  
  The 'reference' property is a number and may be specified as:
    - An int or float
  
  Returns
  -------
  int|float
docstr_tok: ["Sets","the","reference","value","to","compute","the","delta",".","By","default",",","it","is","set","to","the","current","value",".","The","'reference","'","property","is","a","number","and","may","be","specified","as",":","-","An","int","or","float","Returns","--","--","--","-","int|float"]
code: def reference(self):
      """
      Sets the reference value to compute the delta. By default, it
      is set to the current value.
  
      The 'reference' property is a number and may be specified as:
        - An int or float
  
      Returns
      -------
      int|float
      """
      return self["reference"]
  
imports: from plotly.basedatatypes import BaseTraceHierarchyType
  import copy
label_desc: Use image node_id 11 for calling the Delta obj's underlying member method code with example usage: obj.reference() and returns: self