append method
Appends a new value onto an existing key inside a FormData object, or adds the key if it does not already exist.
Implementation
void append(String name, Object value, [String? filename]) {
final typedValue = switch (value) {
File file => (null, file.copyWithName(filename)),
Blob blob => (null, File([blob], filename ?? 'blob', type: blob.type)),
String string => (string, null),
_ => (value.toString(), null),
};
_storage.add((name, typedValue));
}