<s>[INST] How do I execute a string containing Python code in Python? How do I execute a string containing Python code in Python?
 [/INST] For statements, use exec(string) (Python 2/3) or exec string (Python 2):
>>> mycode = 'print "hello world"'
>>> exec(mycode)
Hello world

When you need the value of an expression, use eval(string):
>>> x = eval("2+2")
>>> x
4

However, the first step should be to ask yourself if you really need to.  Executing code should generally be the position of last resort: It's slow, ugly and dangerous if it can contain user-entered code.  You should always look at alternatives first, such as higher order functions, to see if these can better meet your needs.
 </s>