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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 diff_commonPrefix(self, text1, text2):
 """Determine the common prefix of two strings. Args: text1: First string. text2: Second string. Returns: The number of characters common to the start of each string. """

    # Quick check for common null cases.
    if not text1 or not text2 or text1[0] != text2[0]:
      return 0
    # Binary search.
    # Performance analysis: https://neil.fraser.name/news/2007/10/09/
    pointermin = 0
    pointermax = min(len(text1), len(text2))
    pointermid = pointermax
    pointerstart = 0
    while pointermin < pointermid:
      if text1[pointerstart:pointermid] == text2[pointerstart:pointermid]:
        pointermin = pointermid
        pointerstart = pointermin
      else:
        pointermax = pointermid
      pointermid = (pointermax - pointermin) // 2 + pointermin
    return pointermid