Type Inference

To declare a variable without specifying an explicit type (either by using the := syntax or var = expression syntax), the variable's type is inferred from the value on the right hand side.

When the right hand side of the declaration is typed, the new variable is of that same type:

var i int
j := i // j is also an int

However, when the right hand side is a literal value (an untyped numeric constant like 42 or 3.14), the new variable will be an int, float64, or complex128 depending on its precision:

i := 42           // int
f := 3.14         // float64
g := 0.867 + 0.5i // complex128

Assignment

Our current price to send a text message is 2 cents. However, it's likely that in the future the price will be a fraction of a penny, so we should use a float64 to store this value.

Edit the penniesPerText declaration so that it's inferred by the compiler to be a float64.