title: Importing function from another cog with discord.py
body: <p>I would like to import some functions from another cog so they can be used for several cogs in different .py files. How would I go about doing that? Here's what the documentation says:</p>
  
  <pre><code>class Economy(commands.Cog):
      ...
  
      async def withdraw_money(self, member, money):
          # implementation here
          ...
  
      async def deposit_money(self, member, money):
          # implementation here
          ...
  
  class Gambling(commands.Cog):
      def __init__(self, bot):
          self.bot = bot
  
      def coinflip(self):
          return random.randint(0, 1)
  
      @commands.command()
      async def gamble(self, ctx, money: int):
          """Gambles some money."""
          economy = self.bot.get_cog('Economy')
          if economy is not None:
              await economy.withdraw_money(ctx.author, money)
              if self.coinflip() == 1:
                  await economy.deposit_money(ctx.author, money * 1.5)
  </code></pre>
  
  <p>as an example, but that means I have to define <code>economy</code> every time if I would like to call on it. Is there a more efficient method for calling a function in another cog?</p>