/// <summary>
/// Retrieves a signed 64-bit integer value for the specified option field,
/// assuming a zigzag encoding.
/// </summary>
/// <param name="field">The field to fetch the value for.</param>
/// <param name="value">The output variable to populate.</param>
/// <returns><c>true</c> if a suitable value for the field was found; <c>false</c> otherwise.</returns>
public bool TryGetSInt64(int field, out long value)
{
ulong?tmp = GetLastNumericValue(field);
value = CodedInputStream.DecodeZigZag64(tmp.GetValueOrDefault());
return(tmp != null);
}