Function parse 

pub fn parse<'a>(input: &'a str) -> IResult<&'a str, Rc<Element<'_>>>

transform svg to a Element(AST struct)

return a result. if transformed successfullly,return a tulp which includes the rest input text and a element; if transformed Error.return ParseError

Example

use svg_simple_parser::parse;
use std::collections::HashMap;

let svg = r#"
    <svg xmlns="http://www.w3.org/2000/svg" version="1.1">
        <circle cx="100" cy="50" r="40" />
    </svg>
"#;
let (_, root) = parse(svg).unwrap();
assert_eq!(root.ele_type, "svg");
assert_eq!(*root.attributes.borrow(), HashMap::from([
    ("xmlns".to_owned(), "http://www.w3.org/2000/svg"),
    ("version".to_owned(), "1.1"),
]));
let child = &*root.children.borrow()[0];
assert_eq!(child.ele_type, "circle");
assert_eq!(*child.attributes.borrow(), HashMap::from([
    ("cx".to_owned(), "100"),
    ("cy".to_owned(), "50"),
    ("r".to_owned(), "40"),
]));