question: private boolean parsePrefixAsIdd ( Pattern iddPattern , StringBuilder number ) { Matcher m = iddPattern . matcher ( number ) ; if ( m . lookingAt ( ) ) { int matchEnd = m . end ( ) ; Matcher digitMatcher = CAPTURING_DIGIT_PATTERN . matcher ( number . substring ( matchEnd ) ) ; if ( digitMatcher . find ( ) ) { String normalizedGroup = normalizeDigitsOnly ( digitMatcher . group ( 1 ) ) ; if ( normalizedGroup . equals ( "0" ) ) { return false ; } } number . delete ( 0 , matchEnd ) ; return true ; } return false ; }
target:  Strips the IDD from the start of the number if present. Helper function used by maybeStripInternationalPrefixAndNormalize.