return true if at least one parameter's key matches the given key
Get the values of all instances of key
Get the values of all instances of key
This is for urls like http://foo.com?bar=val1&bar=val2&bar=val3, which is a valid url
Get the value of a query string parameter when only at most one value is expected.
Get the value of a query string parameter when only at most one value is expected. If there are multiple instances of the parameter then only the value of the first is returned