code: def get_ecosystem_solver(ecosystem_name, parser_kwargs=None, fetcher_kwargs=None):
      
      from .python import PythonSolver
  
      if ecosystem_name.lower() == "pypi":
          source = Source(url="https://pypi.org/simple", warehouse_api_url="https://pypi.org/pypi", warehouse=True)
          return PythonSolver(parser_kwargs, fetcher_kwargs={"source": source})
  
      raise NotImplementedError("Unknown ecosystem: {}".format(ecosystem_name))
docs: Get Solver subclass instance for particular ecosystem.
  
      :param ecosystem_name: name of ecosystem for which solver should be get
      :param parser_kwargs: parser key-value arguments for constructor
      :param fetcher_kwargs: fetcher key-value arguments for constructor
      :return: Solver