text: """A set of basic callbacks for bleach.linkify."""
  from __future__ import unicode_literals
  
  
  def nofollow(attrs, new=False):
      href_key = (None, u'href')
      if href_key not in attrs or attrs[href_key].startswith(u'mailto:'):
          return attrs
  
      rel_key = (None, u'rel')
      rel_values = [val for val in attrs.get(rel_key, u'').split(u' ') if val]
      if u'nofollow' not in [rel_val.lower() for rel_val in rel_values]:
          rel_values.append(u'nofollow')
      attrs[rel_key] = u' '.join(rel_values)
  
      return attrs
  
  
  def target_blank(attrs, new=False):
      href_key = (None, u'href')
      if attrs[href_key].startswith(u'mailto:'):
          return attrs
  
      attrs[(None, u'target')] = u'_blank'
      return attrs
  