def calc_at_skew(sequence):
 a = (sequence.count('A') + sequence.count('a'))
 t = (sequence.count('T') + sequence.count('t'))
 if ((a + t) == 0):
  return 0.0
 else:
  return ((a - t) / float((a + t)))

def calc_at_skew ( sequence ) : a = ( sequence . count ( 'A' ) + sequence . count ( 'a' ) ) t = ( sequence . count ( 'T' ) + sequence . count ( 't' ) ) if ( ( a + t ) == 0 ) : return 0.0 else : return ( ( a - t ) / float ( ( a + t ) ) )
returns the / at skew in a passed sequence .