text: import alertifyjs from 'alertifyjs'
  
  export default function (annotationData, begin, end) {
    // The span cross exists spans.
    if (annotationData.span.isBoundaryCrossingWithOtherSpans(begin, end)) {
      alertifyjs.warning('A span cannot be modifyed to make a boundary crossing.')
      return false
    }
  
    // The span exists already.
    if (annotationData.span.hasDenotationSpan(begin, end)) {
      return false
    }
  
    // There is a BlockSpan that is a child.
    if (annotationData.span.hasBlockSpanBetween(begin, end)) {
      return false
    }
  
    return true
  }
  