code: def _commonprefix(m):
      "Given a list of pathnames, returns the longest common leading component"
      if not m:
          return ''
      prefix = m[0]
      for item in m:
          for i in range(len(prefix)):
              if prefix[:i+1] != item[:i+1]:
                  prefix = prefix[:i]
                  if i == 0:
                      return ''
                  break
      return prefif _commonprefix(m):
      "Given a list of pathnames, returns the longest common leading component"
      if not m:
          return ''
      prefix = m[0]
      for item in m:
          for i in range(len(prefix)):
              if prefix[:i+1] != item[:i+1]:
                  prefix = prefix[:i]
                  if i == 0:
                      return ''
                  break
      return prefix
docs: Given a list of pathnames, returns the longest common leading component