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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 _left_zero_blocks(self, r):
 """Number of blocks with zeros from the left in block row `r`."""

    if not self._include_off_diagonal:
      return r
    elif not self._upper:
      return 0
    elif self._include_diagonal:
      return r
    else:
      return r + 1