Function encode 

pub fn encode(
    precision: u8,
    points: impl IntoIterator<Item = (f64, f64)>,
) -> String

Encodes a sequence of points (latitude, longitude pairs) into a polyline string with the given precision. The precision parameter specifies the number of decimal places in the coordinates (5 for polyline5, 6 for polyline6), with a maximum value of 7 which corresponds to ~1cm precision at the equator.

// Encode an array of latitude/longitude coordinates with precision 5 (standard for Google Maps)
assert_eq!(polyline_iter::encode(5, [(55.58513, 12.99958), (55.61461, 13.04627)]),"angrIk~inAgwDybH");

// `encode()` accepts any iterator that produce (lat,lon)
let iter = (1..5).map(|i| (55.5 + 0.1 * i as f64, 12.9 + 0.1 * i as f64));
assert_eq!(polyline_iter::encode(5, iter), "_kjrI_ajnA_pR_pR_pR_pR_pR_pR");

// And it can be used with slices as well (convert iter of references to iter of values with `copied()`)
let points = vec![
    (55.58513, 12.99958),
    (55.61461, 13.04627),
    (55.64485, 13.11219),
    (55.67816, 13.18223),
    (55.71840, 13.22343),
];
assert_eq!(polyline_iter::encode(5, points[1..3].iter().copied()), "ifmrIebsnA_|D_{K");