input: Write a python function to validate phone numbers using regular expressions.
  assert validate_phone("+1 123-456-7890") == True
  assert validate_phone("123.456.7890") == True
  assert validate_phone("1234567890") == True
  assert validate_phone("(123) 456-7890") == True
  assert validate_phone("123-45-6789") == False
output: import re
  
  def validate_phone(phone_number):
      pattern = re.compile(r"^(?:\+?1\s?)?\(?\d{3}\)?[-.\s]?\d{3}[-.\s]?\d{4}$")
      return bool(pattern.match(phone_number))