def legalize_names(varnames):
    """returns a dictionary for conversion of variable names to legal
    parameter names.
    """
    var_map = {}
    for var in varnames:
        new_name = var.replace("_", "__").replace("$", "_").replace(".", "_")
        assert new_name not in var_map
        var_map[var] = new_name
    return var_map
returns a dictionary for conversion of variable names to legal
    parameter names.
    
numba/core/ir_utils.py