import re

def processArray(array):
    newArray = []
    for l in array:
        m = re.findall(r"[A-Za-z0-9+-]+(?=[^][]*])", " ".join(l))
        if m:
        	newArray.extend(m)
    return newArray

print(processArray([['Preconditions [+Here]\n'], ['Preconditions [+Is', '+The]\n'], ['Preconditions [-Example]\n']]))