import os
def buildHeaders(definition, request, outputs, resolved):
    headers = {}

    for header_name, header_value in definition.headers.items():
        value = header_value

        if isinstance(value, dict) and "output" in header_value:
            value = outputs[value["output"]]

        if isinstance(value, dict) and "os" in header_value:
            value = os.environ.get(value["os"])

        if isinstance(header_value, dict) and "prefix" in header_value:
            value = header_value["prefix"] + value

        headers[header_name] = value

        request["headers"] = headers

    return headers