def dup_strip(f):
 if ((not f) or f[0]):
  return f
 i = 0
 for cf in f:
  if cf:
   break
  else:
   i += 1
 return f[i:]

def dup_strip ( f ) : if ( ( not f ) or f [ 0 ] ) : return f i = 0 for cf in f : if cf : break else : i += 1 return f [ i : ]
remove leading zeros from f in k[x] .