In the initial commit to this project, you have been provided with a basic project setup as well as a set of tests which currently fail. Your task is to create a calculate function which will properly calculate the answer given the array of values given the rules outlined below.

The calculate function runs an arithmetic calculation based upon an array of inputs (eg. [2, '*', 10])

Each input should be either a number or an operand (+, -, *, /)

Our upstream data is inconsistent, so we intentionally accept it and deal with it in the following ways:

• Stringified numbers (eg. '2') should be treated as numbers
• NULL should be treated as zero
• undefined values should be ignored
• Empty string values (eg. '') should be ignored
• Non-numeric values (eg. 'foo') should be ignored