add phone_validator method (#4552)

* add phone_validator method

* change the phone_validator to indian_phone_validator

* Unnecessary comments removed

* all comments deleted

* Fixes: #{} new line issue

* code reformatted using black

strings/indian_phone_validator.py

@@ -0,0 +1,28 @@
+import re
+
+
+def indian_phone_validator(phone: str) -> bool:
+    """
+    Determine whether the string is a valid phone number or not
+    :param phone:
+    :return: Boolean
+    >>> indian_phone_validator("+91123456789")
+    False
+    >>> indian_phone_validator("+919876543210")
+    True
+    >>> indian_phone_validator("01234567896")
+    False
+    >>> indian_phone_validator("919876543218")
+    True
+    >>> indian_phone_validator("+91-1234567899")
+    False
+    """
+    pat = re.compile(r"^(\+91[\-\s]?)?[0]?(91)?[789]\d{9}$")
+    match = re.search(pat, phone)
+    if match:
+        return match.string == phone
+    return False
+
+
+if __name__ == "__main__":
+    print(indian_phone_validator("+918827897895"))