/// the function returns file-content using given filepath
///
/// # Examples
///
/// ```
/// extern crate drumatech;
/// use drumatech::fileu;
/// let s : String = fileu::filepath_to_content("/path/to/file").unwrap();
/// ```
/// the function returns file-content or raw-strings
///
/// # Examples
///
/// ```
/// extern crate drumatech;
/// use drumatech::fileu;
/// let s : String = fileu::content_or_raw("f main(){ return 30 }");
/// assert_eq!(String::from("f main(){ return 30 }"),s);
/// ```