Create a function in Python for converting currencies from one type to another.
currency_from = 'USD'
currency_to = 'EUR'
exchange_rate = 0.9
def convert_currencies(currency_from, currency_to, exchange_rate):
 return currency_fit * exchange_rate 

c = convert_currencies('USD', 'EUR', 0.9)
print(c) # Output: 0.9