def p_arglist(p):
 if (len(p) == 4):
  p[0] = (p[1] + [p[3]])
 else:
  p[0] = [p[1]]

def p_arglist ( p ) : if ( len ( p ) == 4 ) : p [ 0 ] = ( p [ 1 ] + [ p [ 3 ] ] ) else : p [ 0 ] = [ p [ 1 ] ]
arglist : arglist comma argument | argument .