def comp(seq):
    """ returns a seq with complement. Preserves little n's for splitters."""
    ## makes base to its small complement then makes upper
    return seq.replace("A", 't')\
              .replace('T', 'a')\
              .replace('C', 'g')\
              .replace('G', 'c')\
              .replace('n', 'Z')\
              .upper()\
              .replace("Z", "n")
def comp(seq):
    
    
    return seq.replace("A", 't')\
              .replace('T', 'a')\
              .replace('C', 'g')\
              .replace('G', 'c')\
              .replace('n', 'Z')\
              .upper()\
              .replace("Z", "n")
def comp ( seq ) : ## makes base to its small complement then makes upper return seq . replace ( "A" , 't' ) . replace ( 'T' , 'a' ) . replace ( 'C' , 'g' ) . replace ( 'G' , 'c' ) . replace ( 'n' , 'Z' ) . upper ( ) . replace ( "Z" , "n" )
returns a seq with complement. Preserves little n's for splitters.
returns a seq with complement . Preserves little n s for splitters .