code: def elide_sequence(s, flank=5, elision="..."):
      
  
      elided_sequence_len = flank + flank + len(elision)
      if len(s) <= elided_sequence_len:
          return s
      return s[:flank] + elision + s[-flank:]
docs: trim a sequence to include the left and right flanking sequences of
      size `flank`, with the intervening sequence elided by `elision`.
  
      >>> elide_sequence("ABCDEFGHIJKLMNOPQRSTUVWXYZ")
      'ABCDE...VWXYZ'
  
      >>> elide_sequence("ABCDEFGHIJKLMNOPQRSTUVWXYZ", flank=3)
      'ABC...XYZ'
  
      >>> elide_sequence("ABCDEFGHIJKLMNOPQRSTUVWXYZ", elision="..")
      'ABCDE..VWXYZ'
  
      >>> elide_sequence("ABCDEFGHIJKLMNOPQRSTUVWXYZ", flank=12)
      'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
  
      >>> elide_sequence("ABCDEFGHIJKLMNOPQRSTUVWXYZ", flank=12, elision=".")
      'ABCDEFGHIJKL.OPQRSTUVWXYZ'