DocoptArgumentError.position
size_t position() const @safe pure nothrow @nogcReturns the position (0-based index) in argv where mismatch occurred. If unknown, this may be 0 or a sentinel depending on the throw site.
size_t position() const @safe pure nothrow @nogcReturns the position (0-based index) in argv where mismatch occurred. If unknown, this may be 0 or a sentinel depending on the throw site.