text: #!/usr/bin/env python2.3
  
  """
  Read a MAF from standard input and print average GC content of each alignment
  
  usage: %prog < maf > out
  """
  from __future__ import division, print_function
  
  import sys
  
  from bx.align import maf
  
  
  def __main__():
      
      maf_reader = maf.Reader( sys.stdin )
  
      for m in maf_reader:
          gc = 0
          bases = 0
          for c in m.components:
            gc += c.text.count( 'G' )
            gc += c.text.count( 'C' )
            gc += c.text.count( 'g' )
            gc += c.text.count( 'c' )
            bases += ( len( c.text ) - c.text.count( '-' ) )
  
          print(gc / bases)
  
  if __name__ == "__main__":
      __main__()
  