31Evaluate an Expression

Hardparsingrecursion

Write calculate(expr) that evaluates an arithmetic expression made of whole numbers, +, -, *, brackets and spaces, and returns the integer result.

Multiplication happens before addition and subtraction, and operators of the same kind go left to right, just like in Python.

Examples

Example 1

>>> calculate('2 + 3 * 4')
14

Example 2

>>> calculate('(2 + 3) * 4')
20

Good to know

Don't use eval(). The point is to write the parser yourself.
There is no division and no negative numbers written as -5.

Run examples checks the 2 examples above. Submit runs all 8 tests, including hidden edge cases, and marks the challenge solved.