Function to_query 

pub fn to_query<R>(uri: String, request: &R) -> String
where
    R: Request + ?Sized,

Available on crate feature alloc only.

Serializes a Request to a query string and appends it to the given URI.

This function naively concatenates a query string to uri and if uri already has a query part, it will have a duplicate query part like ?foo=bar?baz=qux.