def find_maxima(x):
    """Find local maxima of x.

    Input arguments:
    x -- 1D list of real numbers

    Output:
    idx -- list of indices of the local maxima in x
    """

    local_maxima = []

    for index, value in enumerate(x):
        if index <= len(x)-2:
            if x[index] > x[index+1] and x[index] > x[index-1]:
                local_maxima.append(index)
    
    if len(local_maxima) > 0:
        return local_maxima