In the doxygen comment of this function, one argument name was prefixed
with a backslash by mistake. Old doxygen versions did not complain
about this, but doxygen-1.8.11 does:
warning: unexpected token in comment block while parsing the argument of command param
/**
* Check if the given string is a valid receiver specifier.
*
- * \param \ra string of the form receiver_name [options...]
+ * \param ra string of the form receiver_name [options...]
* \param lprp Filled in on success, undefined else.
*
* This function checks whether \a ra starts with the name of a receiver,