Given a string of words and numbers. Extract the expression including: 
1. the operator: either addition or subtraction
2. the two numbers that we are operating on

Return the result of the calculation.

Example:

"Panda has 48 apples and loses 4" returns 44

"Jerry has 34 apples and gains 6" returns 40

"loses" and "gains" are the only two words describing operators.

Should be a nice little kata for you :)

Note:
No fruit debts nor bitten apples = The numbers are integers and no negatives

Difficulty: EASY
Starter code: def calculate(string):
	

Solutions:
def calculate(s):
	x = [int(i) for i in s.split() if i.isdigit()]
	return sum(x) if 'gains' in s.split() else x[0] - x[1]


import re

def calculate(string):
	(x, y) = re.findall('\\d+', string)
	if re.search('loses', string):
		s = int(x) - int(y)
	if re.search('gains', string):
		s = int(x) + int(y)
	return s


import re

def calculate(string):
	(a, b) = map(int, re.findall('\\d+', string))
	if 'lose' in string:
		return a - b
	else:
		return a + b


import re
import operator

def calculate(s):
	match_res = re.match('.+\\s(\\d+)\\s.+\\s(loses|gains)\\s(\\d+)\\Z', s.strip())
	try:
		return {'loses': operator.sub, 'gains': operator.add}[match_res.group(2)](int(match_res.group(1)), int(match_res.group(3)))
	except AttributeError:
		raise ValueError('string do not obey sepcific')


import re

def calculate(string):
	return eval(re.sub('[^\\d+-]', '', string.replace('loses', '-').replace('gains', '+')))


from re import findall

def calculate(s):
	(op1, op2) = map(int, findall('(\\d+)', s))
	return op1 + op2 if 'gains' in s else op1 - op2


from operator import add, sub

def calculate(s):
	nums = []
	op = None
	for word in s.split():
		if word.isdigit():
			nums.append(int(word))
		elif word in ('gains', 'loses'):
			op = add if word == 'gains' else sub
	return op(*nums)


calculate = lambda s: eval(''.join([a for a in s.replace('loses', '-').replace('gains', '+') if a in '0123456789+-']))


def calculate(string):
	numbers = [int(x) for x in string.split() if x.isdigit()]
	return numbers[0] + numbers[1] if 'gains' in string else numbers[0] - numbers[1]


import re

def calculate(string):
	(x, y) = [int(n) for n in re.findall('\\d+', string)]
	return x - y + y * 2 * ('gains' in string)