code: def commonprefix(m):
      u"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].lower() != item[:i + 1].lower():
                  prefix = prefix[:i]
                  if i == 0:
                      return u''
                  break
      return prefif commonprefix(m):
      u"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].lower() != item[:i + 1].lower():
                  prefix = prefix[:i]
                  if i == 0:
                      return u''
                  break
      return prefix
docs: u"Given a list of pathnames, returns the longest common leading component