Why is the beginning of the condition for checking characters not written in the implementation?

The absence of an explicit beginning condition for character checks may be related to the use of ranges or functions that already encapsulate the check.

For example, in Go, functions from the unicode package are often used to check characters:

import "unicode"

if unicode.IsLetter(runeVar) {
    // handle letter
}

In such cases, there is no need to explicitly write a condition with a character range, as the IsLetter function already checks if the character is a letter.

If the beginning of the condition is missing in the implementation, it is possible that the check occurs elsewhere or a more general approach is used to avoid code duplication and improve readability.