docstr: Sets the hover text formatting rule using d3 formatting mini-
  languages which are very similar to those in Python. For
  numbers, see:
  https://github.com/d3/d3-format/tree/v1.4.5#d3-format. And for
  dates see: https://github.com/d3/d3-time-
  format/tree/v2.2.3#locale_format. We add two items to d3's date
  formatter: "%h" for half of the year as a decimal number as
  well as "%{n}f" for fractional seconds with n digits. For
  example, *2016-10-13 09:15:23.456* with tickformat
  "%H~%M~%S.%2f" would display "09~15~23.46"
  
  The 'hoverformat' property is a string and must be specified as:
    - A string
    - A number that will be converted to a string
  
  Returns
  -------
  str
code: def hoverformat(self):
      """
      Sets the hover text formatting rule using d3 formatting mini-
      languages which are very similar to those in Python. For
      numbers, see:
      https://github.com/d3/d3-format/tree/v1.4.5#d3-format. And for
      dates see: https://github.com/d3/d3-time-
      format/tree/v2.2.3#locale_format. We add two items to d3's date
      formatter: "%h" for half of the year as a decimal number as
      well as "%{n}f" for fractional seconds with n digits. For
      example, *2016-10-13 09:15:23.456* with tickformat
      "%H~%M~%S.%2f" would display "09~15~23.46"
  
      The 'hoverformat' property is a string and must be specified as:
        - A string
        - A number that will be converted to a string
  
      Returns
      -------
      str
      """
      return self["hoverformat"]
  
imports: from plotly.basedatatypes import BaseLayoutHierarchyType
  import copy
label_desc: Use image node_id 9 for calling the Imaginaryaxis obj's underlying member method code with example usage: obj.hoverformat() and returns: self