docstr: Create a new `hmtx` table, for horizontal metrics.
  
  The `metrics` argument must be a dict, mapping glyph names to
  `(width, leftSidebearing)` tuples.
code: def setupHorizontalMetrics(self, metrics):
      """Create a new `hmtx` table, for horizontal metrics.
  
      The `metrics` argument must be a dict, mapping glyph names to
      `(width, leftSidebearing)` tuples.
      """
      self.setupMetrics("hmtx", metrics)
  
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 19 for calling the FontBuilder obj's underlying member method code with example usage: obj.setupHorizontalMetrics(metrics) without return types