Function count_field 

pub fn count_field<'a, A, T>(
    f: &mut EditForm<'a, A, T>,
    key: &str,
    count: &NumericInput,
    reader: &Reader<'_>,
    handle: Option<Track>,
    set: impl Fn(Edit<'_, A, T>, NumericInput) + 'a,
)

The count field of a pattern in f, keyed key, of count as reader reads the parameters — dragged by handle unless it follows a formula — calling set with the count it is set to: a formula as typed, a number rounded to a whole one of at least one, the seed alone.