docstr: [value1, value2, value3, ...] --> bytearray
  
  Emits a sequence of runs. Each run starts with a
  byte-sized header whose 6 least significant bits
  (header & 0x3F) indicate how many values are encoded
  in this run. The stored length is the actual length
  minus one; run lengths are thus in the range [1..64].
  If the header byte has its most significant bit (0x80)
  set, all values in this run are zero, and no data
  follows. Otherwise, the header byte is followed by
  ((header & 0x3F) + 1) signed values.  If (header &
  0x40) is clear, the delta values are stored as signed
  bytes; if (header & 0x40) is set, the delta values are
  signed 16-bit integers.
code: def compileDeltaValues_(deltas, bytearr=None):
      """[value1, value2, value3, ...] --> bytearray
  
      Emits a sequence of runs. Each run starts with a
      byte-sized header whose 6 least significant bits
      (header & 0x3F) indicate how many values are encoded
      in this run. The stored length is the actual length
      minus one; run lengths are thus in the range [1..64].
      If the header byte has its most significant bit (0x80)
      set, all values in this run are zero, and no data
      follows. Otherwise, the header byte is followed by
      ((header & 0x3F) + 1) signed values.  If (header &
      0x40) is clear, the delta values are stored as signed
      bytes; if (header & 0x40) is set, the delta values are
      signed 16-bit integers.
      """  # Explaining the format because the 'gvar' spec is hard to understand.
      if bytearr is None:
          bytearr = bytearray()
      pos = 0
      numDeltas = len(deltas)
      while pos < numDeltas:
          value = deltas[pos]
          if value == 0:
              pos = TupleVariation.encodeDeltaRunAsZeroes_(
                  deltas, pos, bytearr
              )
          elif -128 <= value <= 127:
              pos = TupleVariation.encodeDeltaRunAsBytes_(
                  deltas, pos, bytearr
              )
          else:
              pos = TupleVariation.encodeDeltaRunAsWords_(
                  deltas, pos, bytearr
              )
      return bytearr
  
imports: from fontTools.misc.fixedTools import fixedToFloat, floatToFixed, floatToFixedToStr, strToFixedToFloat, otRound
  from fontTools.misc.textTools import safeEval
  import array
  from collections import Counter, defaultdict
  import io
  import logging
  import struct
  import sys
label_desc: Use image node_id 15 for calling the TupleVariation obj's underlying member method code with example usage: obj.compileDeltaValues_(deltas, bytearr) and returns: bytearr