optimize grammar

blog/form.py

@@ -7,7 +7,7 @@ from wtforms.validators import Length, EqualTo, Email, InputRequired, Regexp, Nu
 
 class RegisterForm(FlaskForm):
     username = StringField(u'First name',
-                           validators=[InputRequired(message=u'Please input your first name.'), Length(1, 20), Regexp(r'[a-zA-Z0-9]+', message=u"Your first name contain invalid characters.")])
+                           validators=[InputRequired(message=u'Please input your first name.'), Length(1, 20), Regexp(r'[a-zA-Z0-9]+', message=u"Your first name contains invalid characters.")])
     email = StringField(u'Email', validators=[
         InputRequired(message=u'Please input your email.'), Length(1, 20),
         Email(message=u'Invalid email. Please check.')])