Function encode_unquoted_attribute_to_string 

pub fn encode_unquoted_attribute_to_string<S: AsRef<str>>(
    text: S,
    output: &mut String,
) -> &str

Write text used in an unquoted attribute to a mutable String reference and return the encoded string slice. Except for alphanumeric characters, escape all characters which are less than 128.

This appends to output and returns only the new string slice. Use a quoted attribute for an empty value; this function does not add quotes.

The following characters are escaped to named entities:

• & => &
• < => <
• > => >
• " => "

Other non-alphanumeric characters are escaped to &#xHH;.