from time import sleep

def delay(fn, ms, *args):
  sleep(ms / 1000)
  return fn(*args)

delay(lambda x: print(x), 1000, 'later') # prints 'later' after one second

primes=[]
products=[]

def prime(num):
    if num > 1:
        for i in range(2,num):
            if (num % i) == 0:
                return False
        else:
            primes.append(num)
            return True

for n in range(30,1000):
    if len(primes) >= 20:
        break;
    else:
        prime(n)

for previous, current in zip(primes[::2], primes[1::2]):
    products.append(previous * current)
    
print (products)

# Deleting all even numbers from a list
a = [1,2,3,4,5]
del a[1::2]
print(a)

class Rectangle:
    pass

class Square(Rectangle):
    pass

rectangle = Rectangle()
square = Square()

print(isinstance(rectangle, Rectangle))  # True
print(isinstance(square, Rectangle))     # True
print(isinstance(square, Square))        # True
print(isinstance(rectangle, Square))     # False

def sum_of_powers(end, power = 2, start = 1):
  return sum([(i) ** power for i in range(start, end + 1)])

sum_of_powers(10) # 385
sum_of_powers(10, 3) # 3025
sum_of_powers(10, 3, 5) # 2925

""" Currency Converter
----------------------------------------
"""
import urllib.request
import json
def currency_converter(currency_from, currency_to, currency_input):
    yql_base_url = "https://query.yahooapis.com/v1/public/yql"
    yql_query = 'select%20*%20from%20yahoo.finance.xchange%20where%20pair' \
                '%20in%20("'+currency_from+currency_to+'")'
    yql_query_url = yql_base_url + "?q=" + yql_query + "&format=json&env=store%3A%2F%2Fdatatables.org%2Falltableswithkeys"
    try:
        yql_response = urllib.request.urlopen(yql_query_url)
        try:
            json_string = str(yql_response.read())
            json_string = json_string[2:
            json_string = json_string[:-1]
            print(json_string)
            yql_json = json.loads(json_string)
            last_rate = yql_json['query']['results']['rate']['Rate']
            currency_output = currency_input * float(last_rate)
            return currency_output
        except (ValueError, KeyError, TypeError):
            print(yql_query_url)
            return "JSON format error"
    except IOError as e:
        print(str(e))
currency_input = 1
#currency codes : http://en.wikipedia.org/wiki/ISO_4217
currency_from = "USD"
currency_to = "TRY"
rate = currency_converter(currency_from, currency_to, currency_input)
print(rate)