def _get_variables(formula, type_):
    """Finds all the variables in the formula of the specific pysmt type.
    
    Args:
        formula (FNode): The pysmt formula to examine.
        type_: The pysmt type to find (e.g: REAL, BOOL).
        
    Returns:
        set(FNode): The set of all the variables in the formula of the specific type.
        
    """
    return {a for a in formula.get_free_variables() if a.get_type() == type_}