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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def format_atomic(value):
 """Format atomic value This function also takes care of escaping the value in case one of the reserved characters occurs in the value. """

    # Perform escaping
    if isinstance(value, str):
        if any(r in value for r in record.RESERVED_CHARS):
            for k, v in record.ESCAPE_MAPPING:
                value = value.replace(k, v)
    # String-format the given value
    if value is None:
        return "."
    else:
        return str(value)