def METHOD_NAME(self, region):
    variable_manager = self.variable_kb.variables[self.func.addr]
    expr_counter = ExpressionCounter(region, variable_manager)
    variable_assignments = {}
    variable_uses = {}
    variable_assignment_dependencies = {}
    # pre-process and identify folding candidates
    # for variable definitions with loads, we invoke StoreStatementFinder to see if there are any Store statements
    # before the definition site and the use site.
    var_with_loads = {}
    single_use_variables = []
    for var, uses in expr_counter.uses.items():
        if len(uses) == 1 and var in expr_counter.assignments and len(expr_counter.assignments[var]) == 1:
            definition, deps, loc, has_loads = next(iter(expr_counter.assignments[var]))
            if has_loads:
                # the definition has at least one load expression. we need to ensure there are no store statements
                # between the definition site and the use site
                _, use_expr_loc = next(iter(uses))
                if isinstance(use_expr_loc, ExpressionLocation):
                    use_loc = use_expr_loc.statement_location()
                else:
                    use_loc = use_expr_loc
                var_with_loads[var] = (loc, use_loc)
            else:
                single_use_variables.append(var)
    store_finder = StoreStatementFinder(region, set(var_with_loads.values()))
    for var, tpl in var_with_loads.items():
        if not store_finder.has_store(*tpl):
            single_use_variables.append(var)
    for var in single_use_variables:
        definition, deps, loc, _ = next(iter(expr_counter.assignments[var]))
        # make sure all variables that var depends on has been assigned at most once
        fail = False
        for dep_var in deps:
            if dep_var.is_function_argument:
                continue
            if dep_var in expr_counter.assignments and len(expr_counter.assignments[dep_var]) > 1:
                fail = True
                break
        if fail:
            continue
        if isinstance(definition, ailment.Stmt.Call):
            # clear the existing variable since we no longer write to this variable after expression folding
            definition = definition.copy()
            if definition.ret_expr is not None:
                definition.ret_expr = definition.ret_expr.copy()
                definition.ret_expr.variable = None
        variable_assignments[var] = definition, loc
        variable_uses[var] = next(iter(expr_counter.uses[var]))
        variable_assignment_dependencies[var] = deps
    # any variable definition that uses an existing to-be-removed variable cannot be folded
    all_variables_to_fold = set(variable_assignments)
    for var in all_variables_to_fold:
        if all_variables_to_fold.intersection(variable_assignment_dependencies[var]):
            del variable_assignments[var]
            del variable_uses[var]
    # replace them
    ExpressionFolder(variable_assignments, variable_uses, region, variable_manager)
    return region