parameters: (self, host, port=None, scheme="http", pool_kwargs=None)
return_statement: return self.connection_from_context(request_context)
docstring: Get a :class:`ConnectionPool` based on the host, port, and scheme.
  
          If ``port`` isn't given, it will be derived from the ``scheme`` using
          ``urllib3.connectionpool.port_by_scheme``. If ``pool_kwargs`` is
          provided, it is merged with the instance's ``connection_pool_kw``
          variable and used to create the new connection pool, if one is
          needed.
docstring_summary: Get a :class:`ConnectionPool` based on the host, port, and scheme.
docstring_tokens: Get a : class : ConnectionPool based on the host port and scheme .
function: def connection_from_host(self, host, port=None, scheme="http", pool_kwargs=None):
          """
          Get a :class:`ConnectionPool` based on the host, port, and scheme.
  
          If ``port`` isn't given, it will be derived from the ``scheme`` using
          ``urllib3.connectionpool.port_by_scheme``. If ``pool_kwargs`` is
          provided, it is merged with the instance's ``connection_pool_kw``
          variable and used to create the new connection pool, if one is
          needed.
          """
  
          if not host:
              raise LocationValueError("No host specified.")
  
          request_context = self._merge_pool_kwargs(pool_kwargs)
          request_context["scheme"] = scheme or "http"
          if not port:
              port = port_by_scheme.get(request_context["scheme"].lower(), 80)
          request_context["port"] = port
          request_context["host"] = host
  
          return self.connection_from_context(request_context)
function_tokens: def connection_from_host ( self , host , port = None , scheme = "http" , pool_kwargs = None ) : if not host : raise LocationValueError ( "No host specified." ) request_context = self . _merge_pool_kwargs ( pool_kwargs ) request_context [ "scheme" ] = scheme or "http" if not port : port = port_by_scheme . get ( request_context [ "scheme" ] . lower ( ) , 80 ) request_context [ "port" ] = port request_context [ "host" ] = host return self . connection_from_context ( request_context )