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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _float_to_bits(value, lower=-90.0, middle=0.0, upper=90.0, length=15):
 """Convert a float to a list of GeoHash bits."""

  ret = []
  for i in range(length):
    if value >= middle:
      lower = middle
      ret.append(1)
    else:
      upper = middle
      ret.append(0)
    middle = (upper + lower) / 2
  return ret