process.py

def process(node):

    if isinstance(node, ast.Num):
        return str(node.n)
    elif isinstance(node, ast.Name):
        return node.id
    elif isinstance(node, ast.Str):
        return r"\b%s\b" % node.s
    elif isinstance(node, ast.Expr):
        return process(node.value)
    elif isinstance(node, ast.BinOp):
        # It's a binary op so we recursively call the binary op methods.
        if isinstance(node.op, ast.Mult):
            return and_(process(node.left), process(node.right))
        elif isinstance(node.op, ast.Add):
            return or_(process(node.left), process(node.right))
    elif isinstance(node, ast.UnaryOp):
        # This is actually negations.
        operand = node.operand
        if isinstance(operand, ast.Name):
            return negate(operand.id)
        elif isinstance(operand, ast.Str):
            return negate(operand.s)
        elif isinstance(operand, ast.Num):
            return negate(operand.n)