s = '{any {possible} characters}{anything}'
r1 = string.gsub(s, '{[^{}]*}$', '')
print(r1)
r3 = string.gsub('{anything}{any {possible} characters}', '%b{}$', '')
print(r3)
cyA9ICd7YW55IHtwb3NzaWJsZX0gY2hhcmFjdGVyc317YW55dGhpbmd9JwpyMSA9IHN0cmluZy5nc3ViKHMsICd7W157fV0qfSQnLCAnJykKcHJpbnQocjEpCgpyMyA9IHN0cmluZy5nc3ViKCd7YW55dGhpbmd9e2FueSB7cG9zc2libGV9IGNoYXJhY3RlcnN9JywgJyVie30kJywgJycpCnByaW50KHIzKQ==