text: import re
  
  def validate_name(data):
      errors = {}
      if 'name' in data and data['name'] != '':
        if not re.match(r"^[a-zA-Z0-9\.\-_]+$", data['name']):
          errors['name']=f"name contains invalid characters"
        if re.match(r"^[\.\-_]", data['name']) or re.match(r".*[\.\-_]$", data['name']):
          errors['name']='name must start and end with a letter or number'
      return errors