Instanciates (loads) pipeline from a source code file.
        
        Arguments:
        
          - filename(``path``) location of the pipeline source code.

def load(self, filename):
        """
        Instanciates (loads) pipeline from a source code file.
        
        Arguments:
        
          - filename(``path``) location of the pipeline source code.
          
        """
        dir_name = os.path.dirname(filename)
        mod_name = os.path.basename(filename).split('.')[0]
        self.filename = mod_name
        sys.path.insert(0, dir_name)
        mod = __import__(mod_name)
        sys.path.remove(dir_name) # do not pollute the path.
        pipers, xtras, pipes = mod.pipeline()
        self.add_pipers(pipers, xtras)
        self.add_pipes(pipes)