Write a function named calculate_discount() that takes two dictionaries: base_prices and discounts. Both dictionaries have strings as keys and integers as values. For each item in base_prices, if there is an item with the same key in discounts, subtract the discounts value from the base_prices value. Return a dictionary with the new, discounted prices. If there was no discount for a given item, return it as it was. For instance, for the following input data:

base_prices = {
  'shoes': 235,
  't-shirt': 49,
  'pullover': 109
}

discounts = {
  'shoes': 40,
  'pullover': 9
}

Your function should return the following dictionary:

discounted_prices = {
  'shoes': 195,
  't-shirt': 49,
  'pullover': 100
}