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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 inasafe_exposure_summary_field_values(field, feature, parent):
 """Retrieve all values from a field in the exposure summary layer. """

    _ = feature, parent  # NOQA

    layer = exposure_summary_layer()
    if not layer:
        return None

    index = layer.fields().lookupField(field)
    if index < 0:
        return None

    values = []
    for feat in layer.getFeatures():
        value = feat[index]
        values.append(value)

    return str(values)