If you're faced with an input box, like this:

                                           +--------------+
  Enter the price of the item, in dollars: |              |
                                           +--------------+

Do you put the $ sign in, or not? Inevitably, some people will type a $ sign and others will leave it out. The instructions could be made clearer - but that won't help those people who never read instructions anyway.

A better solution is to write code that can handle the input whether it includes a $ sign or not.

So, write a simple function that converts a string representing a number into the number itself. Your function should be able to handle negatives!

Examples:

money_value("12.34") => 12.34
money_value("-0.89") => -0.89
money_value(" .11") => 0.11
money_value("007") => 7

Tests:
money_value("-$ 0.1")
money_value("12.34")
money_value("$-2.3456")
money_value("$.2")

Good luck!

This challenge comes from geoffp on CodeWars. Thank you to CodeWars, who has licensed redistribution of this challenge under the 2-Clause BSD License!

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