code: function exact(context, value) {
    var data = context.data
    var flags = context.flags
    var codes = own.call(data, value) ? data[value] : null
    var compound
    var index
    var length
  
    if (codes) {
      return !flag(flags, 'ONLYINCOMPOUND', codes)
    }
  
    compound = context.compoundRules
    length = compound.length
    index = -1
  
    // Check if this might be a compound word.
    if (value.length >= flags.COMPOUNDMIN) {
      while (++index < length) {
        if (value.match(compound[index])) {
          return true
        }
      }
    }
  
    return false
  }
docs: Check spelling of `value`, exactly.