Create a function that takes an array of hashes (groceries) which calculates the total price and returns it as a number. A grocery hash has a product, a quantity and a price, for example:

{
  "product" => "Milk",
  "quantity" => 1,
  "price" => 1.50
}

Examples

# 1 bottle of milk:
get_total_price([
  { "product" => "Milk", "quantity" => 1, "price" => 1.50 }
]) ➞ 1.5

# 1 bottle of milk & 1 box of cereals:
get_total_price([
  { "product" => "Milk", "quantity" => 1, "price" => 1.50 },
  { "product" => "Cereals", "quantity" => 1, "price" => 2.50 }
]) ➞ 4

# 3 bottles of milk:
get_total_price([
  { "product" => "Milk", "quantity" => 3, "price" => 1.50 }
]) ➞ 4.5

# Several groceries:
get_total_price([
  { "product" => "Milk", "quantity" => 1, "price" => 1.50 },
  { "product" => "Eggs", "quantity" => 12, "price" => 0.10 },
  { "product" => "Bread", "quantity" => 2, "price" => 1.60 },
  { "product" => "Cheese", "quantity" => 1, "price" => 4.50 }
]) ➞ 10.4

# Some cheap candy:
get_total_price([
  { "product" => "Chocolate", "quantity" => 1, "price" => 0.10 },
  { "product" => "Lollipop", "quantity" => 1, "price" => 0.20 }
]) ➞ 0.3

Notes

There might be a floating point precision problem in here...