import re


def GetExamplesTextFromDocOptText(DocOptText):
    """Get script usage example lines from a docopt doc string. The example text
    line start from a line containing `Examples:`  keyword at the beginning of the line.
    
    Arguments:
        DocOptText (str): Doc string containing script usage examples lines starting with
            a line marked by `Examples:` keyword at the beginning of a line.

    Returns:
        str : A string containing text lines retrieved from the examples section of
            DocOptText parameter.

    """
    
    ExamplesStart = re.compile("^Examples:", re.IGNORECASE)
    ExamplesEnd = re.compile("^(Author:|See also:|Copyright:)", re.IGNORECASE)
    
    ExamplesText = 'Examples text is not available';
    ExamplesTextFound = False
    
    for Line in DocOptText.splitlines():
        if ExamplesStart.match(Line):
            ExamplesText = 'Examples:';
            ExamplesTextFound = True
            continue
        
        if ExamplesEnd.match(Line):
            break
        
        if ExamplesTextFound:
            ExamplesText += "\n" + Line;
    
    return ExamplesText