<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def infographic_header_element(impact_function_name, feature, parent):
 """Get a formatted infographic header sentence for an impact function. For instance: * infographic_header_element('flood') -> 'Estimated impact of a flood' """

    _ = feature, parent  # NOQA
    string_format = infographic_header['string_format']
    if impact_function_name:
        header = string_format.format(
            impact_function_name=impact_function_name)
        return header.capitalize()
    return None