Unwraps an Option, returning the value of type T, or printing to the stderr buffer the
error text as per the format string and its format arguments specified within the macros
arguments in case is None.
Unwraps a Result<T, E>, returning the value of type T, or printing to the stderr buffer the
error text as per the std::fmt::Display trait implemented for the error E.
Unwraps a Result<T, E>, returning the value of type T, or printing to the stderr buffer the
error text as per the format string and its format arguments specified within the macros
arguments.