ashapochka
diff --git a/‎strings/is_polish_national_id.py‎
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+def is_polish_national_id(input_str: str) -> bool:
+    """
+    Verification of the correctness of the PESEL number.
+    www-gov-pl.translate.goog/web/gov/czym-jest-numer-pesel?_x_tr_sl=auto&_x_tr_tl=en
+
+    PESEL can start with 0, that's why we take str as input,
+    but convert it to int for some calculations.
+
+
+    >>> is_polish_national_id(123)
+    Traceback (most recent call last):
+        ...
+    ValueError: Expected str as input, found <class 'int'>
+
+    >>> is_polish_national_id("abc")
+    Traceback (most recent call last):
+        ...
+    ValueError: Expected number as input
+
+    >>> is_polish_national_id("02070803628") # correct PESEL
+    True
+
+    >>> is_polish_national_id("02150803629") # wrong month
+    False
+
+    >>> is_polish_national_id("02075503622") # wrong day
+    False
+
+    >>> is_polish_national_id("-99012212349") # wrong range
+    False
+
+    >>> is_polish_national_id("990122123499999") # wrong range
+    False
+
+    >>> is_polish_national_id("02070803621") # wrong checksum
+    False
+    """
+
+    # check for invalid input type
+    if not isinstance(input_str, str):
+        msg = f"Expected str as input, found {type(input_str)}"
+        raise ValueError(msg)
+
+    # check if input can be converted to int
+    try:
+        input_int = int(input_str)
+    except ValueError:
+        msg = "Expected number as input"
+        raise ValueError(msg)
+
+    # check number range
+    if not 10100000 <= input_int <= 99923199999:
+        return False
+
+    # check month correctness
+    month = int(input_str[2:4])
+
+    if (
+        month not in range(1, 13)  # year 1900-1999
+        and month not in range(21, 33)  # 2000-2099
+        and month not in range(41, 53)  # 2100-2199
+        and month not in range(61, 73)  # 2200-2299
+        and month not in range(81, 93)  # 1800-1899
+    ):
+        return False
+
+    # check day correctness
+    day = int(input_str[4:6])
+
+    if day not in range(1, 32):
+        return False
+
+    # check the checksum
+    multipliers = [1, 3, 7, 9, 1, 3, 7, 9, 1, 3]
+    subtotal = 0
+
+    digits_to_check = str(input_str)[:-1]  # cut off the checksum
+
+    for index, digit in enumerate(digits_to_check):
+        # Multiply corresponding digits and multipliers.
+        # In case of a double-digit result, add only the last digit.
+        subtotal += (int(digit) * multipliers[index]) % 10
+
+    checksum = 10 - subtotal % 10
+
+    return checksum == input_int % 10
+
+
+if __name__ == "__main__":
+    from doctest import testmod
+
+    testmod()