title: ImportError: cannot import name 'TelField' from 'wtforms'
body: <p>Out of curiosity, I'm trying to use the html 5 widget TelField of Flask WTF.
  However, I get the following error:</p>
  
  <p>ImportError: cannot import name 'TelField' from 'wtforms'</p>
  
  <pre><code>from flask_wtf import FlaskForm
  from wtforms import StringField, PasswordField, SubmitField, TelField
  from wtforms.validators import DataRequired, Email, EqualTo, Length, Optional
  from wtforms.widgets.html5 import TelInput
  </code></pre>
  
  <pre><code>class SignupForm(FlaskForm):
      ...
  
      phone = TelField('Phone', validators=[Length(min=10), DataRequired()])
  
      ...
      submit = SubmitField('Signup')
  </code></pre>
  
  <pre><code>&lt;fieldset class="phone"&gt;
    {{ form.phone.label }}
    {{ form.phone(placeholder='+27123456789') }}
    {% if form.phone.errors %}
       &lt;ul class="errors"&gt;
          {% for error in form.phone.errors %}
             &lt;li&gt;{{ error }}&lt;/li&gt;{% endfor %}
       &lt;/ul&gt;
          {% endif %}
  &lt;/fieldset&gt;
  </code></pre>
  
  <p>I am not sure where I am going wrong with this. Any pointers would be greatly welcomed.
  Thanks in advance.</p>