docstr: Adds an font variations table to the font.
  
  Args:
      axes (list): See below.
      instances (list): See below.
  
  ``axes`` should be a list of axes, with each axis either supplied as
  a py:class:`.designspaceLib.AxisDescriptor` object, or a tuple in the
  format ```tupletag, minValue, defaultValue, maxValue, name``.
  The ``name`` is either a string, or a dict, mapping language codes
  to strings, to allow localized name table entries.
  
  ```instances`` should be a list of instances, with each instance either
  supplied as a py:class:`.designspaceLib.InstanceDescriptor` object, or a
  dict with keys ``location`` (mapping of axis tags to float values),
  ``stylename`` and (optionally) ``postscriptfontname``.
  The ``stylename`` is either a string, or a dict, mapping language codes
  to strings, to allow localized name table entries.
code: def setupFvar(self, axes, instances):
      """Adds an font variations table to the font.
  
      Args:
          axes (list): See below.
          instances (list): See below.
  
      ``axes`` should be a list of axes, with each axis either supplied as
      a py:class:`.designspaceLib.AxisDescriptor` object, or a tuple in the
      format ```tupletag, minValue, defaultValue, maxValue, name``.
      The ``name`` is either a string, or a dict, mapping language codes
      to strings, to allow localized name table entries.
  
      ```instances`` should be a list of instances, with each instance either
      supplied as a py:class:`.designspaceLib.InstanceDescriptor` object, or a
      dict with keys ``location`` (mapping of axis tags to float values),
      ``stylename`` and (optionally) ``postscriptfontname``.
      The ``stylename`` is either a string, or a dict, mapping language codes
      to strings, to allow localized name table entries.
      """
  
      addFvar(self.font, axes, instances)
  
imports: from .ttLib import TTFont, newTable
  from .ttLib.tables._c_m_a_p import cmap_classes
  from .ttLib.tables._g_l_y_f import flagCubic
  from .ttLib.tables.O_S_2f_2 import Panose
  from .misc.timeTools import timestampNow
  import struct
  from collections import OrderedDict
label_desc: Use image node_id 15 for calling the FontBuilder obj's underlying member method code with example usage: obj.setupFvar(axes, instances) without return types