def laceStrings(s1, s2):
    """
    s1 and s2 are strings.

    Returns a new str with elements of s1 and s2 interlaced,
    beginning with s1. If strings are not of same length,
    then the extra elements should appear at the end.
    """
    blendStr = []
    tinyStr = min(s1, s2, key=len)
    for num in range(len(tinyStr)):
        blendStr.append(s1[num])
        blendStr.append(s2[num])
    blendStr = ''.join(blendStr)
    if len(s1) != len(s2):
        tinyStr = len(tinyStr)
        blendStr = blendStr + max(s1, s2, key=len)[tinyStr:]
    return blendStr