Data creates custom form based on the given form data who can have files and string based fields.
Fields creates a new multipart form based on string based fields.
File creates a new multipart form based on a unique file field from the given io.ReadCloser stream.
Files creates a multipart form based on files fields.
DataFields represents a map of text based fields.
FormData represents the supported form fields by file and string data.
FormFile represents the file form field data.
Values represents multiple multipart from values.