def add_modules(self, modules):
    for module in modules:
      if self.modules.get(module.path, None):
        raise KeyError('A module with the path "%s" is already defined' % (
            module.path))
    for module in modules:
      self.modules[module.path] = module
method to output the read coverage by position in the mir
dataset/ETHPy150Open google/anvil-build/anvil/project.py/Project.add_modules--crossover with--dataset/ETHPy150Open ARTbio/tools-artbio/unstable/local_tools/class_mirparser.py/Mirna.density